CHARACTERIZATION OF COPLANAR WAVE-GUIDE OPEN-END CAPACITANCE - THEORYAND EXPERIMENT

The theory, numerical analysis, analytical approximate formula, measur ement technique, and characteristic curves were presented in this pape r for the characterization of coplanar waveguide open end capacitance. A novel variational equation was proposed in terms of the scalar pote ntial on the slot aperture and was solved by applying the finite eleme nt method. With the available analytical Green's function and exact in tegration formulas in the space domain, this approach was found to be quite efficient and suitable for analyzing the coplanar waveguide disc ontinuity problems even with more complicated geometrical configuratio ns. Numerical results were compared to those obtained numerically and experimentally in previous literature, but did not correlate very well . An analytical formula under narrow-slot assumption was thus derived to render a verification of numerical results. Measurement by utilizin g the resonance method were also made and the experimental data confir med the validity of our theory. The relationship between the capacitan ce and the physical dimensions was also investigated. The characterist ic curves of the open end capacitance were obtained. Also, an empirica l formula was established for the open end structures with a thick sub strate and narrow gap.